GIS Tutorial 1

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GIS Tutorial 1

• Lecture 8
• Spatial Data Processing

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Outline

• Attribute extraction
• Feature location extraction
• Location proximities
• Geoprocessing tools
• Model builder

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Attribute extraction

• Lecture 8

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Attribute query extraction

• You have tracts for an
• entire state, but want
• tracts for one county
• only

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Attribute query extraction

• Select tracts by County FIPS ID
• Cook County 031

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Attribute query extraction

• Cook County tractsselected
• Export to new featureclass or shapefile

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Export selected features

• Right-click to export selected features

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Add new layer

• Cook County tracts

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Feature location extraction

• Lecture 8

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Select by location

• Powerful function unique to GIS
• Identify spatial relationships between layers
• Finds features that are within another layer

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Select by location

• Have Cook County census tracts but want City of
  Chicago only
• Cant use Select By Attributes
• No attribute for Chicago
• Use Municipality layer
• City Chicago is a municipality within Cook County

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Select by location

• Select Chicago from municipalities layer

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Select by location

• Selection, Select By location

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Export selected features
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location proximities

• Lecture 8

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Points near polygons

• Health officials want to know polluting companies
  near water features

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Points near points

• School officials want to know what schools are
  near polluting companies

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Polygons intersecting lines

• Transportation planner wants to know what
  neighborhoods are affected by construction
  project on major highway

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Lines intersecting polygons

• Public works official wants to know what streets
  or sidewalks will be affected by potential floods

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Polygons completely within polygons

• City planners want to know what buildings are
  completely within a zoning area.

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Geoprocessing tools

• Lecture 8

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Geoprocessing overview

• GIS operations to manipulate data
• Typically take input data sets, manipulate, and
  produce output data sets
• Often use multiple data sets

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Common geoprocessing tools

• Analysis
• Extract Clip
• Overlay intersect and union
• Data management
• Generalization - dissolve
• General
• Append
• Merge

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Accessing tools

• Geoprocessing menu

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Accessing tools

• ArcToolbox

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Accessing tools

• Search window

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Clip

• Acts like a cookie cutter to create a subset of
  features

Clip features (Central Business District)
Input features (streets)
Output features (CBD streets)
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Clip
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Clip vs select by location

• Clip
• Clean edges
• Looks good
• Select by location
• Dangling edges
• Better for geocoding

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Dissolve

• Combines adjacent polygons to create new, larger
  polygons
• Uses common field value to remove interior lines
  within each polygon, forming the new polygons
• Aggregate (sums) data while dissolving

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Dissolve

• Create regions using U.S. states
• Use SUB_REGION field to dissolve
• Sum population

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Dissolve
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Dissolve results

• States dissolved to form regions
• Population summed for each region

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Append

• Appends one or more data sets into an existing
  data set
• Features must be of the same type
• Input datasets may overlap one another and/or the
  target dataset
• TEST option field definitions of the feature
  classes must be the same and in the same order
  for all appended features
• NO TEST option Input features schemasdo not
  have to match the target feature classes's schema

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Append

• DuPage and Cook County are combining public works
  and need a new single street centerline file.

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Append

• Append will add DuPage streets to Cook County
  streets

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Resultant layer

• One street layer (Cook County) with all records
  and field items

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Merge

• Combines multiple input datasets of the same data
  type into a single, new output dataset
• Illinois campaign manager needs a single voting
  district map but wants to preserve the original
  layers

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Merge
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Resultant layer

• New voting district layer

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Union

• Overlays two polygon layers
• Resulting output layer has combined attribute
  data of the two inputs
• Contains all the polygons from the inputs,
  whether or not they overlap

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Union

• Neighborhoods and ZIP Codes

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Union
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Union

• Better describes characteristics of a
  neighborhood.
• Central business district 15222 vs 15219

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Union

• Attributes tables contain different fields and
  data

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Union results

• New polygons with combined data

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Intersect

• Computes a geometric intersection of the Input
  Features
• Features (or portions of features which overlap
  in all layers and/or feature classes) will be
  written to the Output Feature Class
• Inputs can have different geometry types

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Intersect

• City manager needs to know what buildings
  intersect flood zones and wants the flood data
  attached to each intersecting building

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Intersect
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Intersect result

• Only building polygons that intersect flood zones
  with combined data fields

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Model builder

• Lecture 8

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Model builder overview

• Workflow processes can be complicated
• Models automate and string functions together
• Example
• You have census tracts for a county and want to
  create neighborhoods for a city
• Many steps are needed to create neighborhoods
  (join, dissolve, etc)

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Starting map

• TIGER census tracts and municipalities

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Final map

• Tracts dissolved to create neighborhoods

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Crosswalk table

• Neighborhood names are not included with the
  census tracts, so a crosswalk table was created
  with the name of neighborhood for each census
  tract
• Some neighborhoods are made of multiple tracts

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Set geoprocessing options

• Geoprocessing, geoprocessing options

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Create a new toolbox

• Catalog

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Create a new model

• Right-click new Toolbox

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Add tool to model

• Add Join Tool
• To join crosswalk table to tracts

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Set parameter for Join Tool

• Joins crosswalk table to census tracts

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Model steps

• Add Join
• Dissolve
• Remove join

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Finished model
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Summary

• Attribute extraction
• Feature location extraction
• Location proximities
• Geoprocessing tools
• Model builder